Connected sensor substrate for blister packs

ABSTRACT

A blister pack for dispensing medication comprises a substantially flat backing, a plurality of blisters formed on the backing, first and second sets of conductive traces applied to the backing, a plurality of breakable resistive traces applied to the backing, and a controller adapted to detect breakage of the resistive traces under the blisters by measuring the voltage across each of either the first set of conductive traces or the second set of conductive traces. The blisters are arranged in a grid comprising rows of blisters and columns of blisters. Each of the first set of conductive traces is associated with one of the rows of blisters. Each of the second set of conductive traces is associated with one of the columns of blisters. For each blister, one or more of the resistive traces are applied to the backing under the blister to form a subcircuit, and the subcircuit connects one of the first set of conductive traces with one of the second set of conductive traces.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/202,343 filed Jul. 5, 2016, which claims the benefit of U.S.Provisional Patent Application No. 62/188,618 filed Jul. 3, 2015, thecontents of all of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to the field of packaging and inparticular, to the field of sensors for use in medication packaging.

BACKGROUND OF THE INVENTION

Blister packaging is commonly used to store medication. This type ofpackaging typically comprises a number of blisters formed by athermoformed plastic that is attached to a backing made of paperboard,metallic material, or plastic. One or more pills or tablets may bestored within each of the cavities formed by the blisters. When thepatient wishes to take the medication, he or she simply ruptures theportion of the backing corresponding to the appropriate blister torelease the stored medication.

One example of a blister packaging for medication contains 28 cavities,arranged in 4 columns and 7 rows of cavities. Each row may correspond toa day of the week, with each column corresponding to a particular timeof day (e.g. morning, afternoon, evening, bedtime, etc.). This packagingallows the patient to store a medication regimen for an entire weekusing a single blister pack.

In order to ensure that medication is taken in accordance with aprescribed schedule, blister packs may be provided with electronic means(e.g. circuits) for detecting when the cavities are ruptured. However,if such electronic means are bulky or cumbersome, these “smart” blisterpacks may face difficulties in market adoption since pharmacies may havelimited shelf space. Furthermore, the cost of producing the smartblister packs should not be so high such that pharmacies and patientsare discouraged from using them.

For example, United States Patent Publication No. 2015/0148947 toMcConville et al. discusses a device for determining when a medicationis removed from a blister pack. Each blister of the blister pack has acorresponding circuit on the backing with a different resistanceassociated with each circuit. When a cavity is ruptured, thecorresponding circuit is broken, resulting in a reduction in the overallresistance in the device, which is detected by a controller. AlthoughMcConville et al. discusses the possibility of printing circuitsdirectly on the backing of the blister pack, limitations in the printingprocess typically results in a high degree of variability in theresistances in the resulting circuits. This makes the approach inMcConville et al. impractical when a large number of blisters isrequired, as it is very difficult to ensure that the resistances in eachof the circuits will be sufficiently differently from one another to bedistinguishable when a circuit is broken.

U.S. Pat. No. 8,960,440 to Kronberg also discusses a device formonitoring when cavities on a blister pack are ruptured. The devicecomprises a number of breakable resistive traces (each applied to thebacking of a cavity) connected in parallel to each other, which isconnected in series with a reference resistive trace. When a cavity isruptured, the corresponding resistive trace is broken, resulting in amicrocontroller detecting a change in the ratio of the resistance of the(parallel) breakable resistive traces with respect to the referenceresistive trace. Although the device in Kronberg is able to detect thata cavity has been ruptured, it is not able to detect which particularcavity has been ruptured.

There is therefore a need for a blister pack that is both cost-effectiveto produce and yet capable of detecting when particular cavities areruptured.

SUMMARY OF THE INVENTION

According to one embodiment of the invention, a blister pack fordispensing medication comprises a substantially flat backing, aplurality of blisters formed on the backing, a plurality of breakableresistive traces, a plurality of conductive traces, a power source forapplying electrical power to the resistive traces and the conductivetraces, and a controller. The blisters and the backing form cavities forcontaining the medication, and each blister is coupled with anotherblister to form pairs of blisters. One or more of the resistive tracesare applied to the backing under each blister. For each pair ofblisters, the one or more resistive traces under a first blister of thepair of blisters is connected in parallel by the conductive traces withthe one or more resistive traces under a second blister of the pair ofblisters. The controller detects breakage of the resistive traces underthe blisters for each pair of blisters by measuring the voltage acrossthe resistive traces under each pair of blisters.

In another embodiment, the one or more resistive traces under the firstblister are connected in series. The one or more resistive traces underthe second blister are connected in series.

In yet another embodiment, the one or more resistive traces under thefirst blister are connected in series by one or more of the conductivetraces. The one or more resistive traces under the second blister areconnected in series by one or more of the conductive traces.

In a further embodiment, for each pair of blisters, the one or moreresistive traces under the first blister have a first total resistanceand the one or more resistive traces under the second blister have asecond total resistance, wherein the first total resistance is differentfrom the second total resistance.

In yet a further embodiment, the ratio between the second totalresistance and the first total resistance is between approximately 1.55and 1.7 to 1.

In still yet a further embodiment, the ratio between the second totalresistance and the first total resistance is approximately 1.6 to 1.

In another embodiment, the second total resistance is approximately 80kΩ and the first total resistance is approximately 50 kΩ.

In still another embodiment, the blister pack further comprises aplurality of pads for connection with the controller, wherein the padsare connected to the pairs of blisters by the conductive traces.

In still yet another embodiment, each pad is connected to two pairs ofblisters.

In a further embodiment, the controller is located on the backing.

In still a further embodiment, the blister pack further comprises aspine attached to the backing, wherein the pads are located on the spineand wherein the conductive traces extend from the backing onto thespine.

In yet a further embodiment, the controller is located on the spine.

In another embodiment, the resistive traces and the conductive tracesare printed on the backing. The resistive traces can be printed usingcarbon ink. The conductive traces can be printed using conductive silverink.

In yet another embodiment, the blister pack further comprises acontroller module for housing the controller. The controller module canbe adapted to transmit data comprising data on breakage of the resistivetraces under the blisters.

In a further embodiment, a blister pack for dispensing medicationcomprises a substantially flat backing, a plurality of blisters formedon the backing, a plurality of breakable resistive traces, a pluralityof conductive traces, a power source, and a controller for detectingbreakage of the resistive traces under the blisters. The blisters andthe backing form cavities for containing the medication. The blistersare arranged in a grid comprising columns, wherein each blister iscoupled with another blister in an adjacent column to form pairs ofblisters. For each blister, one or more of the resistive traces areapplied to the backing under the blister to form a subcircuit. For eachpair of blisters, the subcircuit under a first blister of the pair ofblisters is connected in parallel by the conductive traces with thesubcircuit under a second blister of the pair of blisters to form a pairof subcircuits. The conductive traces extend from the ends of each pairof subcircuits. The power source applies electrical power to thesubcircuits. The controller detects breakage of the resistive tracesunder the blisters for each pair of subcircuits by measuring the voltageacross each pair of subcircuits.

In still a further embodiment, for each pair of subcircuits, thesubcircuit under the first blister has a first total resistance and thesubcircuit under the second blister has a second total resistance. Thefirst total resistance is different from the second total resistance.

In another embodiment, a substrate for application on a blister packcomprising blisters comprises a plurality of breakable resistive tracesapplied to the substrate, a plurality of conductive traces applied tothe substrate, a power source, and a controller. For each of theblisters, one or more of the resistive traces are applied to thesubstrate under the blister to form a subcircuit and wherein eachsubcircuit is coupled with another subcircuit to form pairs ofsubcircuits. For each pair of subcircuits, a first subcircuit isconnected in parallel by the conductive traces to a second subcircuit,wherein the conductive traces extend from the ends of each pair ofsubcircuits. The power source applies electrical power to thesubcircuits. The controller detects breakage of the resistive traces inthe subcircuits for each pair of subcircuits by measuring the voltageacross each pair of subcircuits.

In yet another embodiment, the substrate further comprises an adhesivefirst surface for application of the substrate on the blister pack.

In still yet another embodiment, the substrate further comprises asecond surface, wherein the resistive traces and the conductive tracesare applied to the second surface.

In a further embodiment, a system for tracking medication use comprisesa blister pack, a gateway, and a server. The blister pack comprises asubstantially flat backing, a plurality of blisters formed on thebacking, a plurality of breakable resistive traces, a plurality ofconductive traces, a power source for applying electrical power to theresistive traces and the conductive traces, a controller, and atransmitter. The blisters and the backing form cavities for containingthe medication, and each blister is coupled with another blister to formpairs of blisters. One or more of the resistive traces are applied tothe backing under each blister. For each pair of blisters, the one ormore resistive traces under a first blister of the pair of blisters isconnected in parallel by the conductive traces with the one or moreresistive traces under a second blister of the pair of blisters. Thecontroller detects breakage of the resistive traces under the blistersfor each pair of blisters by measuring the voltage across the resistivetraces under each pair of blisters. The transmitter transmits dataregarding breakage of the blisters. The gateway comprises a gatewayreceiver for receiving the data and a gateway transmitter fortransmitting the data. The server comprises a server receiver forreceiving the data, an analysis module to compare the data with apredetermined schedule for medication use to determine adherence withthe schedule, and a communications module for sending notificationsregarding the adherence with the schedule.

In another embodiment, a blister pack for dispensing medicationcomprises a substantially flat backing, a plurality of blisters formedon the backing, a first set of conductive traces applied to the backing,a second set of conductive traces applied to the backing, a plurality ofbreakable resistive traces applied to the backing, a power sourceconfigured to selectively apply electrical power to one or more of thefirst set of conductive traces or the second set of conductive traces,and a controller adapted to detect breakage of the resistive tracesunder the blisters by measuring the voltage across each of either thefirst set of conductive traces or the second set of conductive traces.The blisters and the backing form cavities for containing themedication, and the blisters are arranged in a grid comprising rows ofblisters and columns of blisters. Each of the first set of conductivetraces is associated with one of the rows of blisters such that all ofthe blisters for each row of associated blisters is connected. Each ofthe second set of conductive traces is associated with one of thecolumns of blisters such that all of the blisters for each column ofassociated blisters is connected. For each blister, one or more of theresistive traces are applied to the backing under the blister to form asubcircuit, and the subcircuit connects one of the first set ofconductive traces with one of the second set of conductive traces.

In still a further embodiment, each of the subcircuits has a totalresistance, and the total resistance for each of the subcircuits issubstantially identical to one other.

In yet still a further embodiment, the total resistance is approximately10 kΩ.

In yet another embodiment, the blister pack further comprises a selectoradapted to selectively choose one of the first set of conductive tracesto input to the controller.

In still yet another embodiment, the controller is further adapted todetermine iteratively whether resistive traces under each of theblisters have been broken.

In a further embodiment, a blister pack for dispensing medicationcomprises a substantially flat backing, a controller, a plurality ofblisters formed on the backing, a plurality of breakable resistivetraces applied to the backing, and a plurality of conductive tracesapplied to the backing. The blisters and the backing form cavities forcontaining the medication, and wherein each of the blisters is generallydefined by two opposed long edges and two opposed short edges. For eachblister, one or more of the resistive traces are applied to the backingunder the blister to form a subcircuit, and the one or more of theresistive traces cross each of the long edges and each of the shortedges at least once. The conductive traces connect the subcircuits tothe controller. The controller is adapted to detect breakage of theresistive traces under the blisters by measuring the voltage across thesubcircuits.

In yet a further embodiment, the one or more of the resistive tracescross each of the long edges at least twice and each of the short edgesat least once.

In another embodiment, a blister pack for dispensing medicationcomprises a substantially flat backing, a controller, a plurality ofblisters formed on the backing, a plurality of breakable resistivetraces applied to the backing, and a plurality of conductive tracesapplied to the backing. The blisters and the backing form cavities forcontaining the medication. For each blister, at least two of theresistive traces are applied to the backing under the blister to form asubcircuit, and the resistive traces in the subcircuit are connected inparallel. The conductive traces connect the subcircuits to thecontroller. The controller is adapted to detect breakage of theresistive traces under the blisters by measuring the voltage across thesubcircuits.

In still yet a further embodiment, the subcircuit comprises at leastthree resistive traces connected in parallel.

In another embodiment, each of the blisters is generally defined by twoopposed long edges and two opposed short edges, and for each blister,the resistive traces cross each of the long edges at least twice andeach of the short edges at least once.

In yet another embodiment, the backing comprises a plurality ofperforation perimeters proximate to the perimeters of the blisters. Theperforation perimeters each comprise alternating perforations andunperforated gaps. A first width of the unperforated gap isapproximately 1.5 millimeters proximate to where the resistive tracescross either the long edges or the short edges, and a second width ofthe unperforated gap is approximately 0.3 millimeters elsewhere.

The foregoing was intended as a summary only and of only some of theaspects of the invention. It was not intended to define the limits orrequirements of the invention. Other aspects of the invention will beappreciated by reference to the detailed description of the preferredembodiments. Moreover, this summary should be read as though the claimswere incorporated herein for completeness.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by reference to the drawings thereof, inwhich:

FIG. 1 shows a blister pack generally illustrating the invention;

FIG. 2 is a side view of the backing of the blister pack according tothe invention;

FIG. 3 shows a blister pack illustrating an embodiment of the invention;

FIG. 4 shows a schematic diagram illustrating the embodiment of theinvention of FIG. 3;

FIG. 5 shows a schematic diagram illustrating an equivalent circuit fora portion of the schematic diagram shown in FIG. 4;

FIG. 6 shows another embodiment of the invention where a substrateaccording to the invention is attached to the backing of a blister pack;

FIG. 7. shows another embodiment of the invention with the tracesextending onto the spine;

FIG. 8 shows another embodiment of the invention with the controllermodule attached to the spine;

FIG. 9 shows another embodiment of the invention with the controllermodule located within the blister pack;

FIGS. 10a and 10b are top and bottom views, respectively, of thebreakout board shown in FIG. 9;

FIGS. 11a and 11 b are top and bottom views, respectively, of thebreakout board of FIGS. 10a and 10b with the intermediary connectorattached;

FIG. 12 shows another embodiment of the invention with the tracesextending onto the spine and flap;

FIGS. 13a and 13b are top and bottom views, respectively, of analternative embodiment of the breakout board;

FIGS. 14a and 14b are top and bottom views, respectively, of thebreakout board of FIGS. 13a and 13b with the controller module attached;

FIG. 14c is a top view of the controller module of FIGS. 13a and 13 b;

FIG. 15 is a top view of a compartment for holding the controllermodule;

FIG. 16 is a top view of an embodiment of a controller module with apower source;

FIG. 17 shows the communications among the blister pack, gateway, andserver;

FIG. 18 is an alternate embodiment of the invention;

FIG. 19 is another alternate embodiment of the invention;

FIG. 20 shows a multiplexer chip in accordance with an embodiment of theinvention;

FIG. 21 is another alternative embodiment of the invention;

FIG. 22 is a further embodiment of the embodiment of FIG. 21;

FIG. 23 shows an arrangement of the resistive trace for a blister;

FIG. 24 shows another arrangement of the resistive trace for a blister;

FIG. 25 shows an arrangement of multiple resistive traces for a blister;

FIG. 26 shows another arrangement of multiple resistive traces for ablister; and

FIG. 27 shows an arrangement of perforations for a blister.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a blister pack 100 in accordance with anembodiment of the present invention comprises one or more blisters 102,each of which defines a cavity 104 for holding medication 105 (e.g.tablets, capsules, etc.). The blisters 102 may be formed by athermoformed plastic or any other suitable material. In the embodimentsshown in the figures, the blister pack 100 comprises twenty-eightblisters 102, arranged generally in a grid of four columns 106 (i.e.columns 106 a-106 d) and seven rows 108 (i.e. rows 108 a-108 g). In thisembodiment, each of the rows 108 may represent one day of a week, witheach of the columns 106 representing a particular time in the day fortaking medication. However, it is understood that other numbers ofblisters 102 and other arrangements of blisters 102 may also be used.

The blister pack 100 can also comprise a cover 101 and a spine 103. Thecover 101 and spine 103 provides a covering for the blister pack 100 tohide the blisters 102 from view.

The blisters 102 are attached to a backing 110. The backing 110 ispreferably flat and can be generally made from paperboard, plastic, orany other suitable material. The backing 110 comprises a plurality oftraces 112, which preferably include both conductive traces 114 (shownin gray lines) and breakable resistive traces 116 (shown in thick blacklines). FIG. 3 shows an arrangement of the traces 112 in accordance withan embodiment of the invention. In this embodiment, each of the blisters102 is associated with one or more resistive traces 116, with each ofthe blisters 102 preferably located directly on top of its associatedone or more resistive traces 116 (the location of the blisters 102 aregenerally indicated in dotted line). Preferably, the traces 112 arelocated on the side of the backing 110 opposite the blisters 102;however, it is also contemplated that the traces 112 may be on the sameside of the backing 110 as the blisters 102.

The traces 112 are preferably printed on the backing 110. For example,conductive traces 114 may be printed using highly conductive silver ink,while resistive traces 116 may be printed using carbon ink. Othermethods and techniques for forming the traces 112 may also be used. Forexample, the traces 112 may be stamped onto the backing 110 usingaluminum, copper, and/or other conductive materials.

Referring again to FIG. 3, where the blister 102 is associated with oneor more resistive traces 116, those resistive traces 116 are preferablyconnected together in series by one or more conductive traces 114.However, the resistive traces 116 can also be directly connectedtogether in series. For example, the blister 102 located in column 106 aand row 108 a is associated with five resistive traces 116 connected inseries by four conductive traces 114. The adjacent blister 102 locatedin column 106 b and row 108 a is associated with eight resistive traces116 connected in series by seven conductive traces 114. Other numbersand combinations of resistive traces 116 and conductive traces 114 arealso possible.

The resistive traces 116 associated with each of the blisters 102 (alongwith the conductive traces 114 connecting such resistive traces 116)form subcircuits 118, with each blister 102 being associated with onesuch subcircuit 118. As the resistive traces 116 in each subcircuit 118are connected in series, each subcircuit 118 has an effective resistanceR that is equal to the sum of the individual resistances of theresistive traces 116.

The resistive traces 116 in each subcircuit 118 are preferably arrangedin a serpentine, winding, or otherwise extended manner in order toreliably ensure that when the portion of the backing 110 behind aparticular blister 102 is ruptured, the associated subcircuit 118 isbroken.

Referring again to FIG. 3, the various subcircuits 118 are connected byconductive traces 114 to pads 120, which can then receive a controller122. In the embodiment shown in FIG. 3, there are nine pads 120 (i.e.pads 120 a-120 i). FIG. 4 shows a schematic representation of theconnections between the subcircuits 118. Each subcircuit 118 isconnected in parallel with an adjacent subcircuit 118. For example, eachof the subcircuits 118 in column 106 a is connected in parallel withtheir adjacent subcircuit 118 in column 106 b. Similarly, each of thesubcircuits 118 in column 106 c is connected in parallel with theiradjacent subcircuit 118 in column 106 d. In this manner, thetwenty-eight subcircuits 118 are divided into fourteen pairs 124 ofsubcircuits 118.

The fourteen pairs 124 can be divided into two zones 126 (i.e. zones 126a, 126 b). In the embodiment shown in FIGS. 3 and 4, zone 126 a comprisethe subcircuits 118 in the rows 108 a and 108 b, while zone 126 bcomprise the subcircuits 118 in the rows 108 c and 108 d. However, otherways of dividing the subcircuits 118 are also possible.

A first end 128 of each of the pairs 124 in a particular zone 126 iselectrically connected together in common by conductive traces 114 toone of the pads 120, with each zone 126 being connected to a differentone of the pads 120. For example, in the embodiment shown in FIGS. 3 and4, all of the pairs 124 in zone 126 a are connected on their first ends128 to pad 120 g, while all of the pairs 124 in zone 126 b are connectedon their first ends 128 to pad 120 i. Voltage may be applied to thosepads 120 to which the first ends 128 are connected (represented asV_(ref1), V_(ref2) in FIG. 4).

A second end 130 of each of the pairs 124 is also electrically connectedby conductive traces 114 to the pads 120. In particular, the second ends130 of each pair 124 in a particular zone 126 are each connected todifferent pads 120. However, the second ends 130 of each pair 124 in aparticular zone 126 are also electrically connected to the second ends130 of another pair 124 in another zone 126. For example, in theembodiment shown in FIGS. 3 and 4, the second ends 130 of both pairs 124in row 108 a are electrically connected together (at pad 120 f).Similarly, the second ends 130 of both pairs 124 in row 108 b areelectrically connected together (at pad 120 e). Both pairs 124 in row108 c are electrically connected together at pad 120 d. Both pairs 124in row 108 d are electrically connected together at pad 120 c. Bothpairs 124 in row 108 e are electrically connected together at pad 120 b.Both pairs 124 in row 108 f are electrically connected together at pad120 a. Finally, both pairs 124 in row 108 g are electrically connectedtogether at pad 120 h. Other arrangements for connecting pairs 124 fromtwo different zones 126 are also possible.

FIG. 5 is a schematic representation of the equivalent circuit for aparticular pair 124. The two subcircuits 118 (each having an effectiveresistance R) are connected in parallel. The first end 128 for the pair124 is electrically connected to pad 120 to which voltage may beapplied. The second end 130 is electrically connected to another pad120.

As described above, each of the subcircuits 118 has an effectiveresistance R. For any particular pair 124, the two subcircuits 118 inthat pair 124 would have effective resistances of R₁ and R₂,respectively. Since the two subcircuits 118 in each pair 124 areconnected in parallel, the total effective resistance R_(T) for the pair124 would be as follows:

$R_{T} = \frac{R_{1}R_{2}}{R_{1} + R_{2}}$

If one of the subcircuits 118 in the pair 124 was broken (i.e. theportion of the backing 110 for the blister 102 corresponding to thatsubcircuit 118 is broken), then the total effective resistance R_(T) forthe pair will change. For example, if the subcircuit 118 correspondingto R₁ was broken, then the total effective resistance R_(T) will simplybe equal to R₂. Similarly, if the subcircuit 118 corresponding to R₂ wasbroken, then the total effective resistance R_(T) will be equal to R₁.If both subcircuits 118 in the pair 124 were broken, then this wouldresult in an open circuit.

Accordingly, the overall resistive characteristics of the pair 124 willdepend on whether neither, one, or both of the subcircuits 118 in thepair 124 are broken. This can be determined, for example, by monitoringthe voltage drop across the pair 124.

In order to distinguish between the two subcircuits 118 when only one ofthem is broken, it is necessary that the respective effectiveresistances R₁, R₂ of the two subcircuits 118 be different from oneanother. Because of current limitations in printing technology, avariance of up to ±20% in the actual resistance of printed traces 112 ispossible (compared to the expected resistance). However, if thedifference between the resistances is too great (e.g. R₁>>R₂), then itmay be difficult to discern the change in voltage drop when one of thesubcircuits 118 (e.g. when R₁ is broken).

In view of this, it has been found that the ratio of R₂ to R₁ should bepreferably between approximately 1.55 and 1.7, and more preferably,approximately 1.6. For example, in the embodiment shown in FIGS. 3 and4, the resistances used for R₁ and R₂ are approximately 50 kΩ and 80 kΩrespectively, giving a ratio for R₂/R₁ of approximately 1.6. In theembodiment shown in FIG. 3, each of the resistive traces 116 have aresistance of approximately 10 kΩ. As a result, all of the subcircuits118 in columns 106 a and 106 c have effective resistances ofapproximately 50 kΩ (i.e. five resistive traces 116), while all of thesubcircuits 118 in columns 106 b and 106 d have effective resistances ofapproximately 80 kΩ (i.e. eight resistive traces 116). However, it isimportant to note that the actual resistances used by the varioussubcircuits 118 are not as important as the relative ratio of theresistances of the two subcircuits 118 in each pair.

Although the embodiment in FIG. 3 shows two subcircuits 118 connected inparallel to form pairs 124, it is understood that it is also possible toconnect three or more subcircuits 118 in parallel to form largergroupings. One limitation is the relatively large variance in the actualresistance of printed traces 112 (i.e. up to ±20%); however, withimproved accuracy, it is possible to use three or more subcircuits 118in a grouping and still differentiate as to when a particular subcircuit118 is broken.

In addition, although the embodiment in FIG. 3 shows each subcircuit 118connected in parallel with a vertically adjacent subcircuit 118 (in anadjacent column 106), it is understood that horizontally adjacentsubcircuits 118 may be connected together instead. Depending on thenumber of columns 106 and rows 108 in the blister pack 100, the precisearrangement and interconnections of the subcircuits 118 may vary inorder to reduce the number and length of the traces 112, and to evenlyspread the traces 112 between columns 106.

The operation of the blister pack 100 will now be described. Thecontroller 122 may periodically apply voltage at pads 120 g or 120 i. Inparticular, when the blisters 102 in zone 126 a are to be checked todetermine if any of the respective cavities 104 have been ruptured,voltage is applied to pad 120 g. When the blisters 102 in zone 126 b areto be checked, voltage is applied to pad 120 i. In the example wherevoltage is applied to pad 120 g (i.e. to check the blisters 102 in zone126 a), the controller 122 can determine the voltage drop across each ofthe pairs 124 spanning the columns 106 a and 106 b. This is done throughpads 120 a, 120 b, 120 c, 120 d, 120 e, 120 f, and 120 h. The controller122 may use an analog-to-digital converter (ADC) 132 to process thisdata and from this, the controller 122 can determine whether neither,one, or both of the blisters 102 in each pair 124 of zone 126 a havebeen broken. This data can then be stored by the controller 122.

For each pair 124, there are four possible combinations: (1) bothsubcircuits 118 are intact; (2) the first of the subcircuits 118 isbroken but the second of the subcircuits 118 is intact; (3) the first ofthe subcircuits 118 is intact but the second of the subcircuits 118 isbroken; and (4) both subcircuits 118 are broken. Because the resistancesof each of the two subcircuits 118 are different from one another (andpreferably in the ratio of between approximately 1.55 and 1.7), each ofthe four combinations will result in discernible differences, either inthe total effective resistance (in cases (1) to (3)) or in an opencircuit (in case (4)). This can be done for each of the pairs 124 inzone 126 a.

After the results in zone 126 a have been determined, the condition ofthe blisters 102 in zone 126 b can be determined by the controller 122applying voltage to pad 120 i. In a similar manner to that of zone 126a, the condition of the blisters 102 in each of the pairs 124 in zone126 b can be determined.

Consequently, by selectively applying voltage to either pads 120 g or120 i, the condition of each of the blisters 102 on the blister pack 100can be determined. This data can be stored on the controller 122 forfurther processing or transmittal.

By having the second ends 130 of the two pairs 124 in each row 108 sharea common pad 120, it is possible to reduce the number of pads 120required to nine. This allows the use of a smaller controller 122,resulting in a lower cost.

One potential issue with the embodiment shown in FIG. 3 is the presenceof stray or “ghost” current that may interfere with the readings by thecontroller 122. This ghost current is the result of residual currenttravelling through the various subcircuits 118. In order to counteractthis, when the voltage drop for a particular pair 124 in a row 108 isbeing determined by the controller 122, the other rows 108 would be setto “LOW” (or ground). This can be done through the controller 122(through the pads 120). Alternatively, a digital-to-analog converter(DAC) may be used to provide an additional current in the circuit tocancel the ghost current.

The traces 112 can be created by a two-step process of first printingthe conductive traces 114 and then printing the resistive traces 116.

Referring to FIG. 6, instead of applying the traces 112 directly to thebacking 110 of the blister pack 100 (e.g. by printing, etc.), the traces112 may be first applied to an intermediate substrate 158, which is thenapplied to the backing 110 of the blister pack 100. For example, theintermediate substrate 158 can have an adhesive first surface 164 forapplication onto a conventional blister pack. In this manner,conventional blister packs can be converted into “smart” blister packs.The traces 112 can be applied to a second surface 166 of theintermediate substrate 158.

In addition, the backing 110 or the intermediate substrate 158 can beimplemented using only one sheet of material, with graphics printed onone side and the traces 112 applied (e.g. printed) to the other side. Assuch, the backing 110 or the intermediate substrate 158 requires minimallayers, making it easier to punch through to the cavities 104.

Referring to FIG. 1, the controller 122 may be housed within acontroller module 134. The controller module 134 may also comprise apower source 156, such as a battery. In one embodiment, the controllermodule 134 comprises first and second portions 136, 138 defining a slot140 for receiving a portion of one end of the backing 110. In theembodiment shown in FIG. 1, the shape of the controller module 134 isgenerally rectangular; however, it is understood that any shapes may bepossible. The controller module 134 allows for the easy attachment toand detachment from the blister pack 100. The pads 120 make contact withthe inner wall of the first portion 136. The slot 140 is preferably ofsuch thickness to allow for snug attachment of the controller module 134to the backing 110. In the embodiment shown in FIG. 1, the pads 120 andthe controller module 134 are located such that the controller module134 lies flush with the spine 103. This allows for the controller module134 to be easily attached to and detached from the backing 110 withoutfear that the controller module 134 may be misaligned with the pads 120.Alternatively, guides can be printed on the backing 110 to allow for thealignment of the controller module 134 with the pads 120. In addition,physical guides (e.g. made of plastic, paperboard, etc.) can be providedto assist in aligning the controller module 134 with the pads 120.

Referring again to FIGS. 1 and 2, the pads 120 are preferably located onthe backing 110 (or if the intermediate substrate 158 is used, on theintermediate substrate 158), with the controller module 134 directlyconnected to the pads 120 via a sliding or snap-on connection, such asspring pins. In this embodiment, the pins on the controller module 134make direct electrical contact with the pads 120.

In another embodiment, the tight space requirements of the blister pack100 may not leave room for the controller module 134 on the backing 110.In this embodiment, the controller module 134 can instead be located onthe spine 103, as shown in FIGS. 7 and 8. The traces 112 extend acrossthe edge of the backing 110 and onto the spine 134, with the pads 120being located on the spine 134.

In another embodiment, the controller module 134 may be located withinthe blister pack 100 (e.g. within a pocket inside the blister pack 100).The controller module 134 can be attached to the blister pack 100 via anintermediary connector 142, which itself can be attached to the pads120. In the embodiment shown in FIG. 9, the pads 120 are located on thespine 134. The intermediary connector 142 is electrically connected tothe controller module 134 using one or more wires 144. Alternatively,instead of one or more wires 144, a bus wire 146 may also be used toconnect the intermediary connector 142 with the controller module 134.

Referring to FIGS. 10a and 10b , the intermediary connector 142 can beattached to the pads 120 in a number of ways. For example, theintermediary connector 142 can sit on a breakout board 146 that isitself placed over and in electrical contact with the pads 120. Thebreakout board 146 can be securely attached to the spine 134 using glue,conductive tape, or some other form of adhesive. Once the intermediaryconnector 142 has been attached to the pads 120, the controller module134 can be plugged into the intermediary connector 142 using a connectorplug 148, as shown in FIGS. 11a and 11 b.

In another embodiment, the blister pack 100 may further comprise a flap150 extending from either the backing 110 or the spine 126. The traces112 extend across flap 150, with the pads 120 being located on the flap150. For example, in the embodiment shown in FIG. 12, the flap 150extends from the spine 126, with the traces 112 extending across boththe spine 126 and the flap 150. In this manner, the pads 120 can behidden with the blister pack 100 (i.e. the flap 150 can be folded downbetween the spine 126 and the backing 110). With this embodiment, theintermediary connector 142 is not necessary.

FIGS. 13a, 13b, 14a, and 14b shows another embodiment in which thecontroller module 134 and the intermediary connector 142 can both resideon the breakout board 146.

The controller module 134 can be connected into the intermediaryconnector 142 in a number of ways. Ideally, this connection type isselected to enable a snug connection and to provide the ability to keepthe connection without the need for additional points of contact betweenthe controller module 134 and the blister pack 100. The use of aninexpensive connection type will promote the disposable nature of theblister pack 100. Furthermore, the ability to easily attach and detachthe controller module 134 can allow for separation of the blister packs100 from the controller modules 134 during storage and transportation,with assembly required only before dispensing medication. The blisterpacks 100 can themselves be stacked for minimum space occupancy. Thisallows for the blister packs 100 to be used by automated robotic blisterpack dispensing equipment, such as those manufactured by Synmed.

Referring to FIG. 15, the intermediary connector 142 and the controllermodule 134 can be hidden inside a compartment 154 within the blisterpack 100. The compartment 154 may be made from the same material as thebacking 110 (e.g. paperboard, etc.). This allows the intermediaryconnector 142 and the controller module 134 to be protected from damageand hidden from view. When the blister packs 100 are dispensed, thecompartment 154 can be opened to allow for the insertion of thecontroller module 134 and the intermediary connector 142.

In another embodiment (shown in FIG. 16), the size of the controllermodule 134 can be reduced by moving the power source 156 from thecontroller module 134. Instead, the power source 156 may be located onthe backing 110 or on the breakout board 146. The power source 156 isonly needed to remain operative for a limited, defined period of time(e.g. from the moment of the dispensing of the blister pack 100 to theday by which the contents of the blister pack 100 are expected to beused up, plus some additional margin). For example, if the blister pack100 organizes medications for a week, and four blister packs 100 aredispensed for a month, the capacity of the power source 156 can beselected such as to allow all four blister packs 100 to be operative fora little over a month, but not much longer. The power source 156 cancomprise conventional batteries, printable batteries, super capacitors,and the like.

Alternatively, the controller module 134 can also be disposable (ratherthan reusable). In such an embodiment, the controller module 134 caneither reside on its own board or be located directly on the blisterpack 100. Various techniques for accommodating the controller module 134directly on the blister pack 100 can be used, including usingmanufactured or printed components, various adhesives, etc.

Various techniques can also be used in optimizing the determination ofwhen certain blisters 102 are broken. For example, as blisters 102 arebroken, the events are recorded. Later, if there is an ambiguous readingpointing to two or more possible breakages of another blister 102, thecontroller 122 may be able to resolve this by assuming that the sameblisters 102 cannot be broken more than once. By tracking a list ofbroken blisters 102, it may be possible to use elimination to excludeunexpected combinations. Similarly, if blisters 102 are expected to bebroken within a particular time frame and there is aliasing showingalternative combinations of blisters 102 that are supposed to be brokenat other times, the controller 122 can assume the most likelycombination. This can be confirmed by the controller 122 in the futureonce more blisters 102 are broken. In addition, the controller 122 canimplement de-bouncing techniques to check readings multiple times over aperiod of time before confirming.

Furthermore, in addition to detecting the breakage of the blisters 102,the controller 122 can also process data, such as, for example, processdata for communicating the status of the blisters 102 either locally orto a remote service (e.g. through the Internet). This data can then beused and further processed to generate reminders or notifications topatients.

In addition, the controller 122 can implement techniques to extend thelife of the power source 156. For example, if multiple weekly blisterpacks 100 are dispensed over the course of a month, only one blisterpack 100 is likely to be used at a time. One way to minimize the draw ofpower from the power source 156 is the keep the blister packs 100 in“deep sleep” until a certain event is triggered (e.g. the breaking of ablister 102, the picking up of a blister pack 100, etc.). Alternatively,this can be done by utilizing a time driven interrupt, which can be apreprogrammed wakeup value (e.g. once or several times a day or onceevery several days). If the controller 122 detects the triggering eventor the interrupt, the frequency of wakeups can increase, therebyresulting in the blister pack 100 being read more often. The controller122 can also throttle (e.g. decrease) the frequency of wakeups at nightor immediately after the breakage of a blister 102 or at other timeswhen detection is unnecessary.

The controller module 134 preferably has wireless functionality fortransmitting data via the Internet. For example, the controller module134 can comprise a radio or transmitter 135 for short-range low-powerradio interfaces, such as ZigBee, Z-Wave, BLE or its variants, AM/FM, orRF over an open frequency band. Referring to FIG. 17, the controllermodule 134 can connect to a gateway 160 using one or more of theseshort-range radio interfaces. The gateway 160 comprises a gatewayreceiver 170 for receiving data from the radio 135 and a gatewaytransmitter 172 for transmitting data. The gateway 160 can serve as abridge between such short-range radio interfaces and the Internet, usingprotocols such as LTE/GPRS/CDMA or other cellular standards, Wi-Fi,Ethernet, or a combination thereof. The gateway 160 can run frombatteries or some other power supply. The data from the controllermodule 134 may be transmitted to the gateway 160 in real-time forimmediate notification or analysis. Alternatively, the data may bestored by the controller module 134 for later transmittal. In case ofnetwork failure, the gateway 160 can preferably continue to storecaptured data until the network connection is restored.

For example, the gateway 160 may transfer data (e.g. over the Internet,in real-time or in batch) to a central server 162, which can thenanalyze the data to determine whether the blisters 102 are being broken(and implicitly, whether medication is being taken) in accordance with apredetermined schedule. The server 162 comprises a server receiver 174for receiving data from the gateway transmitter 172. The server 162preferably comprises an analysis module 176 for determining whether theblisters 102 are being broken in accordance with the schedule.Notifications or reminders may be sent by the server 162 through acommunications module 178 if, for example, there are deviations from theschedule. The notifications or reminders can be sent by the server 162to the gateway 160 and then from the gateway 160 to the controllermodule 134. Such notifications or reminders can be sent immediately sothat corrective action can be taken as soon as possible.

The need for the gateway 160 comes from the desirability to make thecontroller modules 134 inexpensive. However, if the price of long-rangelow-power wireless radios is sufficiently low, the controller module 134can incorporate such radios for communication directly with theInternet. Examples of such long-range radios include LTE Cat-M1, NB-IoT,EC-EGPRS, eDRX, the latest Wi-Fi, SigFox, LoRa, and other similartechnologies.

Referring to FIG. 18, an alternative embodiment of the blister pack 200comprising blisters 202 and controller module 234 is shown. In thisembodiment, each subcircuit 218 preferably comprises a conductive trace214 and a circuit element 219 extending across it. The circuit elements219 can include resistors, capacitors, or inductors. In addition,conductive traces 214 extend from the pads 220 down the sides of thesubcircuits 218. For example, when the subcircuit 218 in column 206 aand row 208 a is broken (i.e. the conductive trace 214 is broken), thecorresponding circuit element 219 in column 206 a and row 208 a stopsbeing part of the subcircuit 218, thereby changing the circuitparameters.

It is possible to determine the exact blisters 202 that have been openedby detecting the circuit parameters of the subcircuits 218. Inparticular, the values for each of the individual circuit elements 219(i.e. resistances, capacitances, inductances, etc.) are preferablyunique and selected such as to avoid aliasing in the observed outputssuch as voltage, time, and frequency.

For example, if the circuit elements 219 are resistors, then bymeasuring the output voltage across circuit element 219 a, it ispossible to determine which of the blisters 202 are broken in column 206a. If there are N blisters 202, there will be 2^(N) possiblecombinations. The controller 222 can use a lookup table (LUT) approachto decode which of the blisters 202 are broken based on the measuredcircuit parameters.

In order to reduce the number of possible combinations, it is possibleto read multiple subcircuits 218 at a time. For example, it is possibleto read the subcircuits 218 in column 206 a at the same time. Voltage isapplied to pad 220 a, ground is applied to pad 220 b, and high impedanceis applied to pads 220 d, 220 e, 220 f, and 220 g. Current will flowfrom pad 220 a to pad 220 b through the conductive traces 214 associatedwith the subcircuits 218 in column 206 a. If the circuit elements 219are resistors, then pad 220 c is measuring the result of voltage divideracross circuit element 219 a. If one or more subcircuits 218 are broken,the circuit parameters are changed, resulting in a voltage change acrosscircuit element 219 a. When all of the subcircuits 218 are closed (i.e.the blisters 202 are intact), the voltage measured across circuitelement 219 a is highest. As the subcircuits 218 are broken, theparallel resistance of the circuit elements 219 will increase, therebylowering the voltage across circuit element 219 a.

Similarly, the subcircuits 218 in column 206 b can be read. In thiscase, voltage is applied to pad 220 d, ground is applied to pad 220 b,and high impedance is applied to pads 220 a, 220 e, 220 f, and 220 g.Current flows from pad 220 d to pad 220 b and through the subcircuits218 in column 206 b. The voltage across circuit element 219 a ismeasured.

Similarly, the subcircuits 218 in column 206 c can be read. In thiscase, voltage is applied to pad 220 d, ground is applied to pad 220 f,and high impedance is applied to pads 220 a, 220 b, 220 c, and 220 g.Current flows from pad 220 d to pad 220 f and through the subcircuits218 in column 206 c. The voltage across circuit element 219 b ismeasured.

Finally, the subcircuits 218 in column 206 d can be read. In this case,voltage is applied to pad 220 g, ground is applied to pad 220 f, andhigh impedance is applied to pads 220 a, 220 b, 220 c, and 220 d.Current flows from pad 220 g to pad 220 f and through the subcircuits218 in column 206 d. The voltage across circuit element 219 b ismeasured.

It is also possible to use capacitors or inductors instead of resistorsfor the circuit elements 219. For example, if capacitors are used, it ispossible to measure the total capacitance of the subcircuit 218 bymeasuring the time it takes for the capacitors to charge up to aselected voltage level. Precise time measurements using microcontrollercounters enable detecting slight differences in circuit parameters,thereby allowing the determination of which precise subcircuit 218 hasbeen broken.

It is also possible to reduce the number of traces 212, pads 220, andcircuit elements 219 used. As shown in FIG. 19, in the blister pack 300of this embodiment, adjacent subcircuits 318 share the same circuitelement 319, resulting in the number of circuit elements 319 requiredbeing approximately halved. The conductive traces 314 for both of thesubcircuits 318 are electrically connected to the same side of theshared circuit element 319. In order to do so, it may be necessary tohave one of the conductive traces 314 for one subcircuit 318 cross overone the conductive traces 314 extending down the sides. Insulatingmaterial should be used in this cross-over region in order to avoid ashort. Such insulating material may include paper, stickers, glue, etc.In addition, one of the pads 320 can be removed.

Reading the subcircuits 318 in blister pack 300 is as follows. In orderto read the subcircuits 318 in column 306 a, voltage is applied to pad320 a, ground is applied to pad 320 b, and high impedance is applied topads 320 d, 320 e, and 320 f. Current will flow from pad 320 a to pad320 b through the conductive traces 314 associated with the subcircuits318 in column 306 a. The voltage across circuit element 319 a ismeasured.

In order to read the subcircuits 318 in column 306 b, voltage is appliedto pad 320 d, ground is applied to pad 320 b, and high impedance isapplied to pads 320 a, 320 e, and 320 f. Current will flow from pad 320d to pad 320 b. Because high impedance has been applied at pads 320 a,320 e, and 320 f, the shared circuit elements 319 affect only thosesubcircuits 318 in column 306 b. The voltage across circuit element 319a is measured.

In order to read the subcircuits 318 in column 306 c, voltage is appliedto pad 320 e, ground is applied to pad 320 b, and high impedance isapplied to pads 320 a, 320 d, and 320 f. Current will flow from pad 320e to pad 320 b. Because high impedance has been applied at pad 320 a,320 d, and 320 f, the shared circuit elements 319 affect only thosesubcircuits 318 in column 306 c. The voltage across circuit element 319a is measured.

Finally, in order to read the subcircuits 318 in column 306 d, voltageis applied to pad 320 f, ground is applied to pad 320 b, and highimpedance is applied to pads 320 a, 320 d, and 320 e. Current will flowfrom pad 320 f to pad 320 b. Because high impedance has been applied atpad 320 a, 320 d, and 320 e, the shared circuit elements 319 affect onlythose subcircuits 318 in column 306 d. The voltage across circuitelement 319 a is measured.

It is also possible to further reduce the number of pads 320 required byusing a multiplexer (mux) chip 321. The mux chip 321 can be located onthe backing 310 or on some other location on the blister pack 300. Themux chip 321 can aggregate at least a portion of the pads 320 to whichvoltage was previously applied. Referring to FIG. 20, an example of sucha mux chip 321 is shown. The mux chip 321 can output voltage to one ofthe pads 320, while applying high impedance to the other pads 320.

Referring to FIG. 21, an alternative embodiment of the blister pack 400is shown. In this embodiment, each subcircuit 418 is associated with atleast one resistive trace 416. Eleven pads 420 are provided, withconductive traces 414 extending from each of the pads 420. Oneconductive trace 414 corresponds to each of the four columns 406 (i.e.one conductive trace 414 is electrically connected to each of thesubcircuits 418 in one particular column 406, for a total of four suchconductive traces 414). Similarly, one conductive trace 414 correspondsto each of the seven rows 408 (i.e. one conductive trace 414 iselectrically connected to each of the subcircuits 418 in one particularrow 408, for a total of seven such conductive traces 414).

The arrangement shown in FIG. 21 is for a blister pack 400 containingtwenty-eight blisters 402. For blister packs 400 containing a differentnumber of blisters 402, the exact number of conductive traces 414 willbe different.

In order to determine whether the blisters 402 have been broken, thesubcircuits 418 for the blisters 402 are read one at a time. Forexample, voltage is applied to one of the columns 406, and the voltageacross each of the rows 408 is read. If there is a voltage, then currentis going through the subcircuit 418 (i.e. the blister 402 is intact). Ifinstead, there is no voltage, then the subcircuit 418 is broken (i.e.the blister 402 is broken). In order to reduce the effects of ghostcurrent, the pads 420 corresponding to the rows 408 that are not beingread can be set to ground.

The resistive traces 416 may all be of the same or similar resistance.For example, each subcircuit 418 may comprise a resistive trace 416having a resistance of approximately 10 kΩ. However, other resistancesmay also be used.

FIG. 22 shows a diagram of a further embodiment of blister pack 500. Inthis embodiment, the blister pack 500 comprises one or more blisters 502(shown in dotted line) formed on substantially flat backing 510. Theblisters 502 may be arranged generally in a grid of four columns 506(i.e. columns 506 a-506 d) and seven rows 508 (i.e. 508 a-508 g), asshown in FIG. 22. However, it is understood that other numbers ofblisters 502 and other arrangements of the blisters 502 may also beused.

The blister pack 500 further comprises a plurality of conductive traces514 and breakable resistive traces 516, both applied to the backing 510.The conductive traces 514 are arranged into first and second sets 580,581. Each of the conductive traces 514 in the first set 580 is generallyassociated with one of the rows 508. Each of the conductive traces 514in the second set 581 is generally associated with one of the columns506. Therefore, in the embodiment shown in FIG. 22, there would be atotal of 11 conductive traces 514 (i.e. conductive traces 514 a-514 k),one for each of the four columns 506 and one for each of the seven rows508. In other words, conductive traces 514 a-514 g would be part of thefirst set 580, while conductive traces 514 h-514 k would be part of thesecond set 581.

As shown in FIG. 22, all of the blisters 502 in a particular row 508 aretherefore associated with a particular conductive trace 514 from thefirst set 580. For example, all of the blisters 502 in row 508 b areassociated with conductive trace 514 b. Similarly, all of the blisters502 in a particular column 506 would be associated with one particularconductive trace 514 from the second set 581. For example, all of theblisters 502 in column 506 c would be associated with conductive trace514 j. In this manner, each of the blisters 502 would be associated withone conductive trace 514 from the first set 580 and one conductive trace514 from the second set 581.

Each of the blisters 502 is also associated with one or more resistivetraces 516. Preferably, each of the blisters 502 is preferably locatedon top of its associated one or more resistive traces 516. The one ormore resistive traces 516 associated with each of the blisters 502 formsubcircuits 518, with each blister 502 being associated with one suchsubcircuit 518. In the embodiment shown in FIG. 22, the subciruit 518comprises only one resistive trace 516; however, it is understood thatin other embodiments, more than one resistive trace 516 may be connectedtogether to form more complicated circuitry.

As shown in FIG. 22, for each blister 502, its associated subcircuit 518connects its associated conductive trace 514 from the first set 580 withits associated conductive trace 514 from the second set 581. Forexample, the blister 502 located at row 508 c and column 506 d isassociated with conductive traces 514 c and 514 k. The subcircuit 518for that blister 502 would connect conductive trace 514 c to conductivetrace 514 k.

When the backing 510 beneath a particular blister 502 is broken, itsassociated subcircuit 518 would be broken (because of the breakage ofthe resistive traces 516), such that its associated conductive trace 514from the first set 580 would no longer be connected with its associatedconductive trace 514 from the second set 581. Returning to the exampleof the blister 502 located at row 508 c and column 506 d, if the backing510 under that blister 502 was broken, the connection between conductivetrace 514 c and 514 k proximate to that blister 502 would be broken.

As shown in FIG. 22, the conductive traces 514 are preferably applied tothe backing 510 in such a way that they are not directly under any ofthe blisters 502. This is to prevent breakage of the conductive traces514 when the backing 510 under one or more of the blisters 502 isbroken.

The circuitry associated with column 506 a and the circuitry associatedwith row 508 a are shown in enlarged detail in FIG. 22. It is understoodthat similar circuitry may be used for the remaining columns 506 androws 508, respectively.

The conductive traces 514 from the first set 580 are connected to inputs582 of a selector 583, with output 584 of the selector 583 beingconnected to an analog-to-digital converter (ADC) 585 on controller 522.In order to determine whether one of the blisters 502 (e.g. the blister502 located at row 508 c and column 506 d) is open, the followingprocedure may be used. First, in order to minimize the effect of thealternative conductive paths between column-row pairs, row 508 c isselected for testing using the selector 583 such that it is nowconnected to the controller 522. The other rows 508 (i.e. 508 a, 508 b,and 508 d) are tied to ground (to minimize the effect of the commonresistors). Then, column 506 d is connected to ground (0 volts), whilethe other columns 506 are driven to the resulting ADC voltage,effectively isolating all of the columns 506 except for column 506 d.Because the resistance associated with the blister 502 will be differentdepending on whether the associated subcircuit 518 is broken, it will bepossible to determine whether the blister 502 is broken by measuring thevoltage at the ADC 585. For example, it is possible to determine whetherthe blister 502 is open by comparing the measured voltage withpreviously determined values for opened and unopened blisters 502.

Similar steps can be used to test other blisters 502 by selecting theappropriate row 508 and column 506 of the particular blisters 502.

In order to determine which of the blisters 502 in the blister pack 500are open, it is possible to successively iterate through each of therows 508, and for each row, to iterate through each of the columns 506.In this manner, each blister 502 can be tested to determine whether itis open. This information may also be stored by the controller 522.

The subcircuits 518 may all be of the same or similar resistance. Forexample, each subcircuit 518 may comprise a resistive trace 516 having aresistance of approximately 10 kΩ. However, other resistances may alsobe used.

This embodiment reduces the number of conductive traces 514 required,thus making the design of the circuitry easier. In particular, when alarge number of conductive traces 514 are required, it may be difficultto design circuitry on the backing 510 given the minimum trace widthsand spacing requirements.

FIGS. 23 to 26 show possible arrangements of the resistive traces 516relative to the blisters 502. In the arrangements shown in FIGS. 23 to26, the blister 502 is generally rectangular in shape and is generallydefined by two long edges 590 and two short edges 592. In both of thearrangements in FIGS. 23 and 24, the resistive trace 516 crosses each ofthe long edges 590 at two points a, b and crosses each of the shortedges 592 at one point c. Therefore, if the backing 510 under theblister 502 is broken along its edges (i.e. the long edges 590 or theshort edges 592), there are 6 possible locations along its edges wherethe resistive trace 516 may be broken. This would reduce the chance thatan open blister 502 does not result in breakage of the resistive trace516, thereby eluding detection by the controller 522 (i.e. a “falsenegative”).

In cases where the blister 502 has more of a general squareconfiguration, it is also possible to have the resistive trace 516 crosseach of the edges 590, 592 at two points.

On the other hand, in some circumstances, it may be useful to avoid a“false positive” (i.e. where there is an accidental break in theresistive trace 516 but no intended opening of the blister 502).Referring to FIG. 25, a blister 502 and its associated subcircuit 518 isshown. The subcircuit 518 comprises two or more resistive traces 516connected in parallel. In the arrangement shown in FIG. 25, there aretwo resistive traces 516 (i.e. 516 a, 516 b) connected in parallel. Theresistive traces 516 in the subcircuit 518 may be connected in parallelusing conductive traces 514. In order for the subcircuit 518 to read asbroken (thus indicating an open blister 502), it is necessary to breakthe subcircuit 518 at multiple locations. For example, in thearrangement shown in FIG. 25, the subcircuit 518 crosses each of thelong edges 590 at two points a, b and each of the short edges 592 at onepoint c. In order for subcircuit 518 to be considered broken, thesubcircuit 518 must be broken at least at one of points c and at leastone of points a, b. In other words, it is necessary to break thesubcircuit 518 at least at two or more locations on at least twodifferent edges 590, 592 in order to create an open circuit.

FIG. 26 depicts another arrangement of a blister 502 and its associatedsubcircuit 518. In this arrangement, there are three resistive traces516 (i.e. 516 a, 516 b, 516 c) connected in parallel. The resistivetraces 516 may be connected in parallel using conductive traces 514.Depending on how locations on the subcircuit 518 are broken, the overallresistance of the subcircuit 518 will vary, and this can be used to makea determination as to whether the associated blister 502 should beconsidered open. In the arrangement shown in FIG. 26, resistive trace516 a is associated with one of the long edges 590, resistive trace 516c is associated with the other of the long edges 590, and resistivetrace 516 b is associated with the short edges 592. The subcircuit 518crosses each of the long edges 590 at two points a, b and each of theshort edges 590 at one point c. For example, in order to consider theblister 502 open, it may be necessary to have a break on at least two ofthe long and short edges 590, 592, with at least one of the breaks beingon one of the short edges 592.

Referring to FIG. 27, the backing 510 may also comprise a perforationperimeter 594 comprising perforations 596 and located proximate to thelong and short edges 590, 592 of the blister 502. The perforationperimeter 594 allows for easier rupturing of the backing 510. However,the perforation perimeter 594 preferably comprises a plurality ofunperforated gaps 595 between the perforations 596. This provides abalance between making the backing 510 easy to rupture but avoidrupturing the backing 510 (and thus possibly breaking the subcircuits518) by accident. Preferably, the unperforated gaps 595 areapproximately 1.5 mm in width where the perforation perimeter 594crosses the subcircuit 518 and 0.3 mm elsewhere.

Preferably, the resistive traces 516 are printed on the backing 510 andare generally rectangular in shape. If a larger rectangular shape isused for the resistive traces 516, the printing accuracy is improved.Due to the printing process, the edges of the printed resistive traces516 are not even or solid, increasing the level of error. However, theedge distortion has a fixed value as measured in millimeters. As aresult, the smaller the ratio between the edge distortion size to theoverall width of the resistive traces 516, the less error that is causedby the distortion.

It will be appreciated by those skilled in the art that the particularembodiments have been described in some detail but that certainmodifications may be practiced without departing from the principles ofthe invention.

The invention claimed is:
 1. A blister pack for dispensing medication,the blister pack comprising: a substantially flat backing; a pluralityof blisters formed on the backing, wherein the blisters and the backingform cavities for containing the medication, wherein the blisters arearranged in a grid comprising rows of blisters and columns of blisters,and wherein each of the blisters is generally defined by a perimetercomprising a plurality of segments; a first set of conductive tracesapplied to the backing, wherein each of the first set of conductivetraces is associated with a corresponding one of the rows of blisterssuch that for each row of associated blisters, one of the first set ofconductive traces extends along all of the associated blisters; a secondset of conductive traces applied to the backing, wherein each of thesecond set of conductive traces is associated with a corresponding oneof the columns of blisters such that for each column of associatedblisters, one of the second set of conductive traces extends along allof the associated blisters; a plurality of breakable resistive tracesapplied to the backing, wherein for each blister, at least two of theresistive traces are applied to the backing under the blister to form asubcircuit, wherein the resistive traces in the subcircuit are connectedin parallel, wherein each of the resistive traces of the subcircuit isassociated with at least one of the segments; and wherein each ofsubcircuits connects a unique combination of one of the first set ofconductive traces and one of the second set of conductive traces; and acontroller adapted to detect breakage of one or more of the resistivetraces under the blisters by successively isolating each of the firstset of conductive traces and each of the second set of conductive tracesand measuring the voltage across each of either the first set ofconductive traces or the second set of conductive traces to compare adifference in the voltage between the blister that is broken and theblister that is unbroken.
 2. The blister pack of claim 1, wherein eachof the subcircuits has a total resistance, and the total resistance foreach of the subcircuits is substantially identical to one other.
 3. Theblister pack of claim 2, wherein the total resistance is approximately10 kΩ.
 4. The blister pack of claim 1, wherein the plurality of blistersis 28 blisters.
 5. The blister pack of claim 1, wherein the rows ofblisters are 7 rows of blisters.
 6. The blister pack of claim 1, whereinthe columns of blisters are 4 columns of blisters.
 7. The blister packof claim 1, further comprising a selector, wherein the selector isadapted to selectively choose one of the first set of conductive tracesto input to the controller.
 8. The blister pack of claim 1, wherein thecontroller is further adapted to iteratively determine whether resistivetraces under each of the blisters have been broken.
 9. The blister packof claim 1, wherein for each blister, the subcircuit comprises at leastthree resistive traces connected in parallel.
 10. The blister pack ofclaim 1, wherein the segments comprise two opposed long edges and twoopposed short edges.
 11. The blister pack of claim 10, wherein theresistive traces cross each of the long edges at least twice and each ofthe short edges at least once.
 12. The blister pack of claim 11, whereinthe backing comprises a plurality of perforation perimeters proximate tothe perimeters of the blisters, wherein the perforation perimeters eachcomprise alternating perforations and unperforated gaps, and wherein afirst width of the unperforated gap is approximately 1.5 millimetersproximate to where the resistive traces cross either the long edges orthe short edges and a second width of the unperforated gap isapproximately 0.3 millimeters elsewhere.
 13. The blister pack of claim1, wherein the controller is further adapted to determine, based oncomparing the difference in the voltage between the blister that isbroken and the blister that is unbroken and based on the associationbetween the segments and the resistive traces, whether one or more ofthe segments have been broken.